"""Application configuration from environment + runtime overrides."""

from functools import lru_cache
from pathlib import Path

from pydantic_settings import BaseSettings


class Settings(BaseSettings):
    """App settings loaded from env."""

    app_name: str = "Fund Tracer API"
    debug: bool = False

    # Database
    database_url: str = "sqlite+aiosqlite:///./fund_tracer.db"

    # Uploads
    upload_dir: Path = Path("./uploads")
    max_upload_size_mb: int = 20
    allowed_extensions: set[str] = {"png", "jpg", "jpeg", "webp"}

    # LLM
    llm_provider: str = "openai"  # openai | anthropic | deepseek | custom_openai
    openai_api_key: str | None = None
    anthropic_api_key: str | None = None
    deepseek_api_key: str | None = None
    custom_openai_api_key: str | None = None
    custom_openai_base_url: str | None = None
    openai_model: str = "gpt-4o"
    anthropic_model: str = "claude-3-5-sonnet-20241022"
    deepseek_model: str = "deepseek-chat"
    custom_openai_model: str = "gpt-4o-mini"

    class Config:
        env_file = ".env"
        env_file_encoding = "utf-8"
        extra = "ignore"


_runtime_overrides: dict[str, str | None] = {}


def _apply_overrides(settings: Settings) -> Settings:
    for key, value in _runtime_overrides.items():
        if hasattr(settings, key):
            setattr(settings, key, value)
    return settings


@lru_cache
def get_settings() -> Settings:
    return _apply_overrides(Settings())


def update_runtime_settings(payload: dict[str, str | None]) -> Settings:
    """Update runtime settings and refresh cached Settings object."""
    allowed = {
        "llm_provider",
        "openai_api_key",
        "anthropic_api_key",
        "deepseek_api_key",
        "custom_openai_api_key",
        "custom_openai_base_url",
        "custom_openai_model",
    }
    for key, value in payload.items():
        if key in allowed:
            _runtime_overrides[key] = value
    get_settings.cache_clear()
    return get_settings()


def public_settings() -> dict:
    s = get_settings()
    return {
        "llm_provider": s.llm_provider,
        "providers": ["openai", "anthropic", "deepseek", "custom_openai"],
        "models": {
            "openai": s.openai_model,
            "anthropic": s.anthropic_model,
            "deepseek": s.deepseek_model,
            "custom_openai": s.custom_openai_model,
        },
        "base_urls": {
            "custom_openai": s.custom_openai_base_url or "",
        },
        "has_keys": {
            "openai": bool(s.openai_api_key),
            "anthropic": bool(s.anthropic_api_key),
            "deepseek": bool(s.deepseek_api_key),
            "custom_openai": bool(s.custom_openai_api_key),
        },
    }